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Re: Daphnia in hard water



Hello Douglas,

You seem to have "liquid rock" for water! My water is about 400 ppm
hardness -- slightly softer, but not by much -- and several species of
Daphnids live in it OK.

The trick is to VERY SLOWLY aclimate them to your water. Daphnia are
sensitive critters -- that is why they are used for water quality
testing -- and any rapid change in water parameters will likely result
in stress and eventual death.

I would recommend that you, literally, add your water to the starter
culture drop-by-drop (through an air line with a valve or a knot) at
least the first 50% of the fresh water. The slower you add the water,
the less stress on the Daphnia, the more likely the successful survival. 

In similar situations I usually set up a drip overnight, so that I loose
no time fiddling with adding the new water and the critters (crustaceans
or fish) have an easy time getting used to the new water.

Hope it works out fine for you!

Best,

George


> 
> Date: Tue, 13 Feb 2001 11:25:07 -0600
> From: Douglas Guynn <dguynn at nwol_net>
> Subject: Water quality
> 
> Below is an analysis of water from the city where I live;
> 
>                 General
> pH                              7.6
> P. Alkalinity as CaCO3          0       mg/l
> Tot. Alka. As CaCO3             121     mg/l
> Total Hardness as CaCO3 571     mg/l
> Dissolved solids                        1385    mg/l
> Bicarbonate                     148     mg/l
> Carbonate                       0       mg/l
> Dil Conduct                     2814    (umhos/cm)
> Calcium                         126     mg/l
> Chloride                                469     mg/l
> Flouride                                0.4     mg/l
> Magnesium                       62      mg/l
> Total Nitrate                   0.21    mg/l
> Sodium                          263     mg/l
> Sulfate                         380     mg/l
> 
>                 Metals
> Barium                          0.199   mg/l
> Chromium                        < 0.01  mg/l
> Copper                          < 0.006 mg/l
> Iron                            < 0.013 mg/l
> Lead                            < 0.001 mg/l
> Manganese                       0.013   mg/l
> Nickel                          < 0.02  mg/l
> Selenium                        0.0156  mg/l
> Silver                          < 0.01  mg/l
> Sodium                          236     mg/l
> Zinc                            <0.02   mg/l
> 
> Is this water suitable for raising D. magna? If not, could it be mixed with
> RO water to achieve a tolerable dilution, or should I use RO water and one
> of the mineral addititves like RO Right?
> 
> Thoughts?
> 
> Douglas Guynn
> 
> In west Texas, where ANY amount of rain is appreciated.
>